1. Field of the Invention
The present invention relates to a test apparatus.
2. Description of the Related Art
In recent years, various kinds of semiconductor devices are known which are employed in various kinds of electronic devices. Examples of such semiconductor devices include: (i) memory devices such as DRAM (Dynamic Random Access Memory), flash memory, and the like; (ii) processors such as a CPU (Central Processing Unit), an MPU (Micro-Processing Unit), a micro-controller, and the like; and (iii) multifunctional devices such as a digital/analog hybrid device, SoC (System On Chip), and the like. In order to test such semiconductor devices, a semiconductor test apparatus (which will also be referred to simply as “test apparatus”) is employed.
The test items for such semiconductor devices can be broadly classified into functional verification tests (which will also be referred to simply as the “functional tests”) and DC (Direct Current) tests. With a functional verification test, judgment is made whether or not a DUT (device under test) operates normally according to its design. Examples of such a functional verification test include identification of defect positions, and acquisition of evaluation values which indicate the performance of the DUT. Examples of such a DC test include DUT leak current measurement, operation current (power supply current) measurement, breakdown voltage measurement, and the like.
The functional verification test and the DC test have various kinds of specific content for each of the various kinds of semiconductor devices. For example, in the memory functional verification test, first, a predetermined test pattern is written to the memory. Subsequently, the data thus written to the DUT is read out from the memory, and the data thus read out is compared with an expected value so as to generate pass/fail data which represents the comparison result. Although RAM and flash memory are both memory devices, different test patterns are written to the RAM and the flash memory. Furthermore, there is a difference in the writing/readout data units and the writing/readout sequence between the RAM test and the flash memory test.
In a D/A converter functional verification test, a digital signal is supplied to the input terminal of the D/A converter while sweeping the digital signal value in a predetermined range. With such an arrangement, an analog voltage is output from the D/A converter according to the respective digital values, and the analog voltage values thus output are measured. As a result, the offset voltage or the gain is measured.
On the other hand, in an A/D converter functional verification test, an analog voltage is supplied to the input terminal of the A/D converter while sweeping the analog voltage in a predetermined range. With such an arrangement, digital values are output from the A/D converter according to the respective analog voltage values, and the digital values thus output are measured. As a result, the INL (Integral Nonlinearity) or DNL (Differential Nonlinearity) is measured.
Micro-controllers, digital/analog hybrid devices, SoC, and the like, each include various kinds of built-in components such as RAM, flash memory, a D/A converter, and an A/D converter. Thus, there is a need to perform respective functional verification tests for the built-in components.
Furthermore, in many cases, a boundary scan test is executed for such a semiconductor device.
In the present specification, the test item, test pattern format, test sequence, test condition, and the like, are included in the concept that will be referred to as the “test algorithm”.